Dehumidifier that doesn't...

Discussion in 'The Projects Forum' started by wayneh, Nov 6, 2014.

  1. wayneh

    Thread Starter Expert

    Sep 9, 2010
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    Should I just send it to recycle?

    A friend has a Whirlpool dehumidifier that otherwise seems very nice, but it no longer produces water. I took it apart yesterday and found that everything appears to work but it just doesn't condense water. The compressor kicks in and runs (vibrates, anyway) but the coils barely cool. Within 5 minutes or so, the compressor gets hot to the touch and shuts off, even if the control panel is set to "continuous".

    I can get a new compressor for ~$40 but then I'd also need to add a service port and get an R-22 recharge. I'm not sure anyone locally would do that. I did a home air conditioner myself once but recently sold my R-22 on craigslist.

    Does anyone bother to fix these things, or is it time for a drive to the dump?
     
  2. alfacliff

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    Dec 13, 2013
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    a dehumidifier is the same as a refrigerator or airconditioner, compress the freon, remove the heat, let it expand ( which cools) then compress it again. it sounds like the thing is either low on freon or has a plugged filter. if it had been worked on lately, it might have been overfilled. have you cleaned the coils? it uses the evaporator coils to condense the water in the air, then blows the cooled air through the condensor coils to warm it back up before putting it back out. if the coils are plugged up, the pressure will go up and the current on the compressor wil increase.
     
  3. #12

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    There's your diagnostic. The compressor steals its cooling off the flow of Freon.
    If this thing isn't coated with crud and the fan(s) works, you have a Freon leak in a machine so small that leaking an ounce per year will render it more pain than it's worth.

    If this comes down to missing Freon, you know the answer. Check the coils to see if they will sell as copper or aluminum.
     
  4. wayneh

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    I thought I did "know", but wanted a 2nd opinion. Seems like I take a dehumidifier to the recycler every few years. They always fail to the same state - running but doing nothing but adding to my electric bill.

    The coils are copper but I wouldn't expect to be paid. Should I?
     
  5. #12

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    The county west of Tampa includes at least 5 places that pay anywhere from 2 cents a pound for mixed everything, up to 55 cents a pound for copper/aluminum radiators. In my best year, I made more than $400 for all the dead appliances, electric motors, and air conditioner parts that I accumulated. The answer is probably to google, "sell scrap metal" and your county.

    Then consider buying a 6,000 BTU window style air conditioner. It dehumidifies and gives you cold air. In Florida, that's a no-brainer. In your area, think about it. The winters are too cold to need a dehumidifier and the summers, well, think about it.
     
  6. wayneh

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    I estimate my combined coil and piping weight is not more than 2 lbs, so I guess I won't worry about losing out on a couple bucks.

    Dehumidifiers are used around here mostly in basements to keep them nice and dry even during humid weather. Otherwise they get musty when moist air from up above - even air conditioned air - hits the cooler surfaces in the basement. I've often thought it would make more sense to use zoned air conditioning in the basement since, as you say, it would remove heat in addition to moisture. I do have a spot where I could mount a window unit. My friend does too. I think I'll mention it to her.
     
  7. #12

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    You raise a good point. The temperature of the soil changes a lot across distance. In Florida, it's 70 F. In Kentucky, 59 F. In New York, 49 F. The northern states have a range of temperatures that cause condensation.

    An air conditioner is built better than a dehumidifier and does almost exactly the same job. If you don't want the basement colder, consider not installing the air conditioner in a window or wall. If you keep the exhaust heat in the basement, you simply have a dehumidifier that is built better than usual. I named 6,000 BTUs because anything smaller has too narrow of a stable operating range (chronic problems with freezing up). High efficiency in BTUs per watt or SEER is still a good thing for this purpose. There is always a net gain in heat, no matter what the efficiency rating is.

    Trying to use an air conditioner for a dehumidifier pretty much defeats the thermostat on it. Good news: Humidistats have been invented. With proper wiring practices, you can control the A/C with a humidistat and achieve excellent results while minimizing the electrical costs.
     
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  8. sheldons

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    Oct 26, 2011
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    Its obviously got either no refrigerant due to a leak, or a blocked dryer (capillary most likely ) or a faulty compressor- its not just a gas top up you need to find the leak-replace the dryer-change the compressor - vac the system down then check it holds a vacuum then regas.....a lot of work when its easier to go buy a new one
     
  9. crutschow

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    As #12 noted, unless the basement is already warm you may want to just mount it in the room to keep the room warmer. Cooling the basement would tend to keep the humidity higher since relative humidity is a sharp function of temperature. For example, 50% RH at 90F is 100% RH at about 69F. So mounting it in the room would also significantly reduce the amount it would have to run to maintain a desired value of RH.
     
  10. #12

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    It isn't as linear as crutschow might be interpreted. All air conditioners have a, "sensible heat ratio" which means the ratio of energy used to change the F temperature compared to the amount of energy used to remove "latent heat" (water). While the compressor always runs at the same speed, you can decrease the sensible heat change in favor of humidity change by turning the fan speed down.

    Even if you don't have this fan speed option, a 90 degree basement isn't going to start raining at 69 degrees because some of the humidity was removed from the air on the way down to 69 degrees. The graphs converge, but not in a linear way, more gradually.
     
  11. crutschow

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    True. My example was intended to show that cooling down the air means you have to remove more moisture to maintain a given RH setting and that means the air conditioner would have to run more, both to maintain the colder temperature, and also to remove more moisture. Whether to vent the air conditioner to the outside likely depends upon how warm the basement is to begin with and whether the basement is lived in.
     
  12. EllenAnderson

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    Jan 8, 2015
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    I just bumped into this as I am likewise keen on knowing the answer to your question. Likewise, simply pondering about the dehumidifier you purchased. We need one as we have the same issue as you.
     
  13. wayneh

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    The humidifier in question went to the recycling yard 2 months ago, after I pulled the fan and control panel out of it. I have no idea what the owner will do to replace it, but I suspect they will just go buy another "dehumidifier". I'll look hard at a small air conditioner the next time I'm faced with this problem.
     
  14. wayneh

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    Well here I am again with another failing? dehumidifier. Our relatively new unit is icing up its coils. I believe this indicates a low freon level, causing the freon to boil at too low a pressure and temperature. Right?

    I'm getting pretty sick of hauling these to the recycling dump every few years. They're easily the worst appliances in my home for longevity.

    I've been looking at getting a small "portable" air conditioner instead, if it would be more reliable or offer any advantage over yet another dehumidifier. I do not really need to cool my basement any more than now, I just need to pull out the moisture.

    There's a company up the road in Madison, WI that makes a real dehumidifier. I think it would last and do a great job, but it's over $2K! :eek:

    Any words of wisdom? My wife wants to run out and get another of those toy dehumidifiers, and I'm sad that it feels like my only option.
     
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  15. #12

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    You don't need the "portable" part. Just a window unit without using the window. Place it where it can achieve a good "throw" of its cold air so as to entrain a lot of volume of the room air.
     
  16. #12

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    Feeling much better after 90 minutes in the air conditioning and a quart of water ingested and absorbed.:)
    Icing: Diminished air flow over the "cold coil", dirt, air filter, fan motor. I have seen fan motors so weak that a Styrofoam packing worm stopped the movement. Not likely in your case because machines that cheap only have one fan motor for both coils.
    Low Freon: starts as a few loops of, "dry" (non water condensing) coils and localizes as frost in the area nearest the Freon inlet hole. Soon after that, there is not enough Freon to form liquid and the refrigeration effect is too weak to form frost anywhere.
    Chronic icing: Caused by bad design which is not stable for all conditions encountered. The usual limit for failure size is 5000 BTUs or less. Machines of 6000 BTUs and up are (almost) all stable in all expected operating conditions and a few unexpected operating conditions.
    Window air conditioner: A device expected to last at least 10 years. I have one in my shed that is at least 30 years old and still running for the 20 or so hours per year that I need it. (I try to avoid working in the shed in the summer.) The central air on my home was replaced at 30 years old because the increased efficiency of a modern air conditioner was an economic slam-dunk.

    @wayneh
     
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  17. wayneh

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    Yes, that's what I meant. I know there are truly portable units, but I don't need that. So you're an advocate of the window A/C as a better choice than a dehumidifier? The latter is $180-230.
     
  18. crutschow

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    Per #12's discussion it sounds like your "icing" dehumidifier has the proper freon level, just not enough air movement across the coils to keep the coils above the freezing point. Maybe you could add an external fan to boost the air flow.
    What is the room temperature where it's located?
    What happens if you just let it run. Does it frost enough to clog the coils?
     
  19. #12

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    H377 yes! Was I being vague or did that idea get lost in the verbosity?

    An air conditioner is the best dehumidifier you will ever see, but you have to fool it into running heat and cold at the same time. With a window shaker, it's as simple as not using the window.

    Of course, you're allowed to try adding a helper fan to keep it from frosting.
     
  20. #12

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